Maintaining the fuel system in a classic Mercedes Benz 220 D is crucial for ensuring its reliable performance. A key component in this system is the fuel lift pump, responsible for delivering fuel from the tank to the injection pump. Over time, these pumps can experience wear and tear, leading to reduced fuel pressure and impacting engine efficiency. Rebuilding the fuel lift pump can be a cost-effective solution to restore proper function.
Recently, while undertaking a fuel lift pump rebuild on a Mercedes-Benz with a 616.916 engine (similar to those found in some 220 D models of the era), an interesting observation was made regarding the contents of a genuine Mercedes-Benz rebuild kit. The kit, designed for early style pneumatic governed injection pump lift pumps, presented a slight discrepancy compared to expectations based on online parts catalogs and discussions related to later, non-pneumatic pump types often found in W123 or W115 300D models.
Upon opening the kit, it was noted that it contained two o-rings and two valve assemblies, along with anti-corrosion paper, but crucially, no gasket was included. This differed from images and descriptions of later rebuild kits (like the Bosch DGK301) which typically feature copper rings and mounting gaskets. This highlights a key difference between rebuild kits for early and late style pneumatic injection pump lift pumps. It’s essential to verify the contents of your kit against your specific pump type before beginning the rebuild process.
The motivation behind this particular rebuild was to address low fuel pressure and suction, identified through testing with a dealer service lift pump tester, following factory service manual procedures. The vehicle in question, a 1974 240D (W115) with the 616.916 engine, was exhibiting signs of reduced power, prompting a thorough investigation into potential causes. A properly functioning fuel lift pump is paramount for delivering adequate fuel to the injection pump, and any deficiency can manifest as performance issues.
While the absence of a gasket in the kit was unexpected, the rebuild proceeded using the provided components. The expectation is that refreshing the pump with new o-rings and valve assemblies will restore its performance and contribute to improved engine operation. This, combined with planned adjustments to the camshaft and injection pump timing, aims to revitalize the engine’s power output.
For owners of classic Mercedes Benz 220 D models and similar vehicles equipped with early pneumatic injection pump systems, understanding the nuances of fuel lift pump rebuild kits is vital. Always cross-reference part numbers and visually inspect kit contents to ensure they align with your specific vehicle and pump type. Rebuilding the fuel lift pump can be a valuable step in maintaining the performance and longevity of your classic Mercedes diesel.
